Which of the following best represents the ground state electron configuration of a halogen?

• A. ns^2 np^6
• B. ns^2 np^2
• C. ns^2 np^5
• D. ns^2 np^3

Answer: (C)

Verified step by step guidance

1. Recall that halogens are elements found in Group 17 of the periodic table, which means they have seven valence electrons.
2. Understand that the valence electron configuration for main group elements is generally written as \(ns^2 np^x\), where \(n\) is the principal quantum number of the outermost shell and \(x\) is the number of electrons in the p orbital.
3. Since halogens have seven valence electrons, and the s orbital can hold 2 electrons, the remaining electrons must be in the p orbitals, so \(x\) should be 5 to make a total of 7 valence electrons.
4. Compare the given options to find the one that matches \(ns^2 np^5\), which corresponds to 2 electrons in the s orbital and 5 electrons in the p orbital, totaling 7 valence electrons.
5. Conclude that the electron configuration \(ns^2 np^5\) best represents the ground state electron configuration of a halogen.